Reciprocating grinders



2 Sheets-Sheet 1 Filed June 5, 1968 INVENTOR. //E8R7 1*. 353K .ha s

Dec. 15, 1970 H. P. BECK RECIPROCATING GRINDERS 2 Sheets-Sheet 2 Filed June 5, 1968 INV NTOR. HERBERTP .scK

' rvrrwzlvsx United States Patent O US. Cl. 5156 14 Claims ABSTRACT OF THE DISCLOSURE Described herein is an improvement in a grinding machine to reduce over-grinding of the surface of a workpiece in the area at the end of each stroke of a reciprocating grinder which comprises counter reciprocating means and means to limit the forward movement of the reciprocating grinder.

BACKGROUND OF THE INVENTION In the normal processing of certain types of stainless steels and other alloy steels, it is necessary to grind the surface of a hot-rolled plate to smooth the surface to prevent surface defects from manifesting themselves during subsequent operations and spoiling the finished surface of the material. The grinding operation can be performed by hand, but it is preferably performed by a grinding machine of the type described in US. Pat. 3,300,906. In the operation of that machine, a workpiece, such as a plate to be ground, is positioned on the workpiece support means and a gantry or grinder support bridge is positioned so that the grinding wheels supported thereby are disposed at the front or leading edge of the workpiece. The workpiece is preferably positioned on the workpiece support means so that at the extreme limit of movement of the means supporting one of the grinding wheels, that grinding wheel extends just to one of the lateral edges of the workpiece. When the grinders are started, the air cylinder is activated which causes the grinder to reciprocate across the plate to be ground. Simultaneously, a low speed gearhead motor is started to move the gantry slowly along the tracks. The distance the grinders reciprocate is at least equal to the distance between the grinding wheels so that the entire surface of the workpiece will be covered as the grinders reciprocate and as the gantry moves. A conventional solenoid valve is used to control the length of the stroke of the air cylinder and consequently the length of the stroke of the grinders. On grinding machines of the type described in the aforementioned patent, the solenoid valve which affects the reversal of the reciprocating grinders is energized by an electromechanical control device, i.e., limit switch. However, since the limit switch is in a fixed position, the reversal of the grinders movement occurs at the same place (dwell point) each time. This causes overgrinding at the dwell point due to the fact that the grinders forward motion must decelerate, go through zero speed at reversal, and accelerate in the opposite direction. The present invention eliminates over-grinding along a fixed line by spreading the dwell point over a greater area. This is accomplished by activating an electromechanical control device which causes reversal of the reciprocating grinders at a different point each time.

SUMMARY OF THE INVENTION The present invention, used in combination with a reciprocating grinder, causes reversal of the stroke of the reciprocating means, to which the grinder is connected, at random points within a defined distance and thus prevents overgrinding. In general, this can be accomplished by activating an electromechanical control device ice to cause reversal of the stroke, i.e., distance traversed, of the reciprocatinggrinders. And more specifically by operatively connecting the means reciprocating the grinders to a limit switch and separately reciprocating a limit switch trip over a predetermined distance which overlaps a predetermined part of the distance the limit switch is reciprocating.

It is therefore a principal object of the invention to provide a reciprocating grinder machine with means for eliminating overgrinding in the dwell area.

It is another object of this invention to provide means whereby the reversal point of a reciprocating mechanism can be randomly spread over a defined distance.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a front elevation of a grinding machine of the type described in US. Pat. No. 3,300,906 in combination with a specific embodiment of this invention.

FIG. 2 is an elevation of an enlarged portion of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a specific embodiment of this invention includes a gantry designated generally as 10. The gantry 10 includes a center span 12 supported at its opposite ends by a pair of support towers or legs 14 and 16. The support towers 14 and 16 are provided with flanged wheels 18 which are mounted on tracks 20 so that the gantry is movable therealong. The wheels 18 are driven by suitable drive means (not shown) which are connected to the wheels through chain and sprocket system 24.

The gantry 10 spans a workpiece supporting bed 25 which is provided with a plurality of skids (not shown) upon which the workpiece, 25A, e.g. plate to be ground is supported.

The center span 12 of the gantry includes an I-beam frame member 28 which supports a pair of tracks 29. A trolley 30 is mounted on the tracks 29 by means of upper flanged wheels and lower guide wheels (not shown). An air cylinder 33 is mounted on the I-beam frame member 28 and its piston rod 33A is connected to a trolley 30 by a bracket 34 which is bolted to the trolley 30. The air cylinder 33 is connected to a source of compressed air (not shown) in a conventional manner to drive the piston rod and, hence, the trolley 30 reciprocally on the tracks 29.

A plurality of support brackets 35' are secured to the underside of the trolley 30 at regular intervals, and wrist pins 36 pivotally mount grinder support arms 38 to each of the brackets 35.

Grinders 40, each having a conventional grinding wheel 41, are pivotally mounted to the end of each support arm 38. The support arms 38 are adapted to be oscillated in a vertical plane by means of another air cylinder 44. The air cylinder 44 is trunnion mounted on a bracket 46 which is bolted to the trolley 30.

Referring now to FIG. 2, a limit switch 101 mounted on trolley 30, is operatively connected to air cylinder 33 to control the distance the piston rod 33A travels away from the air cylinder 33.

Another air cylinder 102, connected to a source of air (not shown), is mounted on the I-beam frame 28 and its piston rod 102A has adjustably mounted to it a bracket 103 which functions as a limit switch trip. Air cylinder 102, reciprocates the limit switch trip 103 over a distance sufiicient to engage the limit switch 101 after the trolley 30 has traveled at least the distance equal to the distance between grinders. It is the function of the limit switch trip 103 to engage the limit switch 101 and cause reversal of the trolley 30. Since both the limit switch 101 and the limit switch trip 103 are reciprocat ing, actuation of the limit switch 101 will occur at a random point along the overlap of the stroke of the pistons, 33A and 102A.

The air cylinder 102 is the preferred means for activating the limit switch 101. A few examples of some other means for causing reversal of the air cylinder, 33 are: motor and screw; motor and cam; motor, rod and pinion; and, "a hydraulic cylinder.

It is preferred that the piston rod 102A of cylinder 102 reciprocate at a slower rate than that at which piston rod 33A reciprocates, and that such rate be less than A of that of the air cylinder piston 33A. This permits the dwell point to be spread over a greater distance because the probability of the limit switch being tripped is spread over a longer time interval.

To assure tripping of the limit switch 101 by the limit switch trip 3', the stroke of the piston rods from each cylinder must overlap. It is preferable that the distance along which the limit switch trip 103 can and must stroke the limit switch 101, after it has traveled at least a distance equal to the distance between grinders, be 10 inches. This prevents overgrinding by randomly spreading the dwell point over a distance of 10 inches.

Although the invention has been shown in combination with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit particular requirements without departing from the spirit and scope of the invention.

I claim:

1. In combination with a grinding apparatus of the type having a workpiece-support means adapted to support the workpiece in a grinding position, a grinder support bridge spanning said workpiece-support means, a plurality of grinders mounted on said bridge and depending therefrom adapted to grind the surface of said workpiece, and a first reciprocating means to reciprocate said grinder on said bridge, the improvement comprising:

(a) a second reciprocating means adapted to reciprocate in the same direction as the first reciprocating means; and

(b) means for controlling the distance the first reciprocating means reciprocates in relation to the distance the second reciprocating means reciprocates.

2. The improvement as recited in claim 1, wherein the means for controlling the distance said first reciprocating means reciprocates comprises:

(a) a limit switch mounted on one of said first and second reciprocating means, and operatively connected to the first reciprocating means; and

(b) a limit switch trip mounted on the other reciprocating means adapted to trip said limit switch to cause reversal of the stroke of the first reciprocating means.

3. The improvement as recited in claim 1, wherein the means for controlling the distance said first reciprocating means reciprocates comprises:

(a) a limit switch mounted on the first reciprocating means and operatively connected to the first reciprocating means; and

(b) a limit switch trip mounted on the second reciprocating means adapted to trip said limit switch mounted on the second reciprocating means to cause reversal of the stroke of the first reciprocating means.

4. The improvement as recited in claim 3, wherein the second reciprocating means reciprocates at a rate of less than A: of the first reciprocating means.

5. The improvement as recited in claim 3, wherein the limit switch trip reciprocates over a predetermined distance to trip the limit switch after the first reciprocating means has traveled at least a distance equal to the distance between grinders.

6. In combination with a grinding apparatus of the type having a workpiece-supporting bed adapted to support a workpiece in a grinding position, a movable gantry having a center span extending across said supporting bed, tracks on opposite sides of said workpiece-supporting bed on which said gantry moves from one end of said bed to the other, said center span including a frame member and a trolley mounted on said frame member for movement in a direction normal to the direction of travel of the gantry, a plurality of aligned regularly-spaced support arms pivotally carried by said trolley, a grinder pivotally mounted on each of said arms, each of said grinders having a grinding wheel disposed to engage the surface of said workpiece; a first reciprocating means to reciprocate said trolley on said center span, the stroke of said first reciprocating means being at least as great as the space between adjacent support arms, and a drive means to drive said gantry on said tracks, the improvement comprising:

(a) a second reciprocating means adapted to reciprocate in the same direction as the first reciprocating means; and

(b) means for controlling the distance the first reciprocating means reciprocates in relation to the distance the second reciprocating means reciprocates.

7. The improvement as recited in claim 6, wherein the means for controlling the distance said first reciprocating means reciprocates comprises:

(a) a limit switch mounted on one of said first and second reciprocating means and operatively connected to the first reciprocating means; and

(b) a limit switch trip mounted on the other reciprocating means adapted to trip said limit switch to cause reversal of the stroke of the first reciprocating means.

8. The improvement as recited in claim 6, wherein the means for controlling the distance said first reciprocating means reciprocates comprises:

(a) a limit switch mounted on the first reciprocating means and operatively connected to the first reciprocating means; and

(b) a limit switch trip mounted on the second reciprocating means adapted to trip said limit switch mounted on the second reciprocating means to cause reversal of the stroke of the first reciprocating means.

9. The improvement as recited in claim 8, wherein the second reciprocating means reciprocates at a rate of less than Mi of the first reciprocating means.

10. The improvement as recited in claim 8, wherein the limit switch trip reciprocates over a predetermined distance to trip the limit switch only after the first reciprocating means has traveled at least a distance equal tothe distance between grinders.

11. In combination with a grinding apparatus of the type having a workpiece-support means adapted to support the workpiece in a grinding position, a grinder support bridge spanning said workpiece-support means, a plurality of grinders mounted on said bridge and depending therefrom adapted to grind the surface of said workpiece, and a first reciprocating means to reciprocate said grinder on said bridge, the improvement comprising:

(a) an electromechanical control device operatively connected to the first reciprocating means; and

(b) means to activate said control device to cause reversal of the stroke of the reciprocating means, at different points, over a predetermined distance.

12. In combination with a grinding apparatus of the type having a workpiece-supporting bed adapted to support a workpiece ina grinding position, a movable gantry having a center span extending across said supporting bed, tracks on opposite Sides of said workpiece-supporting bed on which said gantry moves from one end of said bed to the other, said center span including a frame member and a trolley mounted on said frame member for movement in a direction normal to the direction of travel of the gantry, a plurality of aligned regularly-spaced support arms pivotally carried by said trolley, a grinder pivotally mounted on each of said arms, each of said grinders having a grinding wheel disposed to engage the surface of said workpiece; a first reciprocating means to reciprocate said trolley on said center span, the stroke of said first reciprocating means being at least as great as the space between adjacent support arms, and a drive means to drive said gantry on said tracks, the improvements comprising:

(a) an electromechanical control device operatively connected to the first reciprocating means; and (b) means to activate said control device to cause reversal of the stroke of the reciprocating means, at different points, over a predetermined distance. 13. The improvement recited in claim 12 wherein the electromechanical control device comprises a limit switch. 14. The improvement recited in claim 13 wherein the means to activate said limit switch comprises a second reciprocating means adapted to reciprocate in the same direction as the first reciprocating means.

References Cited UNITED STATES PATENTS JAMES L. JONES, 112., Primary Examiner 

